One of the largest business problems that retailers face is how to liquidate inventory during the clearance period while maximizing profit yet still following certain business rules and limitations. In retail practice this problem is referred to as markdown optimization. The goal of markdown optimization is to determine which products to mark down, how much to mark them down, when to mark them down, and in which markets or stores. These recommendations can be based on factors such as inventory levels, base sales volume, price elasticity, local preferences, and local demand. Such a series of price decreases devised for a particular item or set of items are typically called a price schedule and are used by retailers to guide them in decreasing or eliminating inventory during the clearance period.